Transcript

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SOLAR ENERGY Solar energy is the ultimate source of energy from millions ofyears and it is a renewable energy. This energy consists of radiant light and heat energy from thesun. Out of all energy emitted by sun only a small fraction ofenergy is absorbed by the earth. Just this tiny fraction of the sun’s energy that hits the earth isenough to meet all our power needs. Using present solar techniques some of the solar energyreaching the earth is utilized for generating electricity etc…. Even then the energy demand met by using solar energy isvery less.

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PRESENT SCENARIO• The fossil fuels are non renewablesources so we can not depend onthem forever.• Though nuclear energy is a cleanand green energy ,as said byDr.A.P.J Abdul Kalam, there arealways some problems associatedwith it.• So the only option we have issolar energy because it is anonpolluting and silent source ofelectricity and also lowmaintainence and long lastingenergy.

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• We can use solar energy by converting it to electrical energy .So we must use a device called solar panels which canconvert the light energy into electrical energy.• Solar panel is a group of solar cells.• Solar cells works on the principle of photoelectric effect.• PHOTOELECTRIC EFFECT• When a light of certain frequency falls on the surface of ametal , electrons will absorb the energy . If incident lightenergy is greater than the work function(minimum energyrequired to remove the loosely bound valence electrons)ofthe metal ,then the photo electrons will be emitted and theexcess energy is converted to the kinetic energy of electron.How solar energy is used

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Working of solar cells• When solar panels are placed in the sunlight , photons willstrike the surface and emits electrons.• As a result electron hole pair is created in the solar cell.• When external circuit is connected to the solar cell, electrons flow in the circuit and the current is generated.

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USES OF SOLAR ENERGY• Heaters Green houses• Cars water pumps• Lights Desalination• Satellites Chilling• Dryers Solar ponds• Calculators Thermal• Commercial useOn an office building , roof areas can be covered with solarpanels .• Remote buildings such as schools , communities canmake use of solar energy.• In developing countries , this solar panels are very muchuseful.• Even on the highways , for every five kilometres ,solartelephones are used.

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BETTER WAYS OF USAGE• Government should take measures and see that solarlights are used as street lights in all the areas.• We can place solar panels in the barren lands instead ofkeeping it away uselessly.• We can also keep these solar panels in the deserts, where we can make use of this energy with the help of arechargeable battery.• Efficiency of solar panels depends on the range offrequencies of light that strikes the surface . So they cangive higher efficiency if we split the light into differentfrequency ranges and direct the beams onto the cellstuned to these frequencies.• Building a new home is the best time to design and orientthe home to take the advantage of the sun’s rays.